Transcript Science Fair Project - Miss Hanson's Biology Resources

Living Factories
Biotechnology
SG Biology
Learning Outcomes 1
• State that the raising of dough and the
manufacture of beer and wine depend
on the activities of yeast.
• Identify yeast as a single celled fungus,
which can use sugar as food
• Using a word equation, state the process
of fermentation of glucose by yeast.
• Describe the process of anaerobic
respiration and compare it with aerobic
respiration
Biotechnology
• Biotechnology is the use of microbes
and raw materials to produce useful
substances.
Biotechnology
Raw
materials
Suitable microorganisms
Biotechnological
process
Products
Services
Food, enzymes
Sewage treatment
Fuels
Water purification
Anti-biotics, hormones
Products of Biotechnology
Structure of Yeast
• Yeast is a single
celled fungus
• It multiplies by
budding
Yeast
• Yeast breaks down glucose into
carbon dioxide and ethanol.
– In bread making, the carbon dioxide
helps the bread to rise.
– In brewing, the yeast turns sugars into
alcohol.
• Present on fruits, such as grapes as a
bloom (grey dust).
Fermentation in Yeast
• Fermentation is respiration in the
absence of oxygen (anaerobic
respiration).
• It can be represented by an equation.
Glucose
carbon dioxide + ethanol + energy
Stages in Bread making
• Add yeast to a warm sugar solution and
allow to grow and produce bubbles.
• Add a pinch of salt to the flour
• Mix together into a dough
• Leave mixture in a warm place covered
by a cloth
• Yeast releases CO2 bubbles making
dough rise
• Bake dough in a hot oven
• Yum Yum
Baking
• Yeast is added to
,
and
.
•
is made which is folded and left
in a warm place.
•
(anaerobic respiration)
causes the yeast to produce ethanol and
carbon dioxide.
• The
causes the dough to rise.
• The dough is then baked in the oven which kills
the yeast and removes the
.
• After baking the bread is ready.
Stages in wine making
Crush grapes to release juice
Filter juice into fermentation tank
Add yeast to grape juice
Yeast grows using sugar and changes it
into alcohol (CO2 is allowed to escape)
• Alcohol becomes concentrated and kills
the yeast
• Wine siphoned into bottles
•
•
•
•
Wine making
•
•
•
•
•
•
are crushed and the
grape juice is filtered off.
is added to the grape juice.
takes place, yeast uses the
sugar in the grape juice to make
and
.
The
is allowed to escape.
As the
builds up it kills the yeast.
The wine is removed into bottles and
allowed to
.
Learning Outcomes 2
• Describe how commercial brewers
provide the best growing conditions
for yeast.
• Explain what is meant by the term
“batch processing”
• Explain the need for malting of barley
before use by the brewing industry.
Growing conditions for Yeast
• Food supply
– Starch is converted to sugar for yeast
by germinating barley grains on the
floor of the malting house (malting)
• Suitable temperature
– Optimum temperature maintained in
fermenter vessel by a thermostat
• Lack of competition
– Other microorganisms killed by boiling
in the wort kettle
Brewing
• A brewer is interested in both the
alcohol and the carbon dioxide made
by the yeast.
– Beer is expected to be alcoholic
– the carbon dioxide gives the
characteristic fizz.
Brewing
• Raw materials
–
–
–
–
–
Barley grains
Water
Extra sugar
Hops
Live yeast
• By products
– Cattle food
– Fertiliser
– Yeast extract
Brewing (1)
• Barely grains which are full of
, which is a large molecule that yeast
can not digest
• Barley grains are allowed to
germinate.
– Starch is converted to
This is called
.
• Yeast is added and
place.
sugar.
takes
Brewing (2)
• Yeast changes the maltose into
carbon dioxide and ethanol.
• As the
level builds up the yeast is
killed.
• Beer is then made and allowed to
.
• To brew the best beer the brewer must
make sure his fermenter vessels are _
and that he uses the
temperature for the yeast.
Learning Outcomes 3
• State that the manufacture of cheese
and yoghurt depends on the activity
of bacteria.
• State that the souring of milk is a
fermentation process.
• Explain the souring of milk in terms of
bacterial fermentation of lactose.
Fermentation of Lactose
• When the bacteria growing in milk
respire anaerobically, they use the milk
sugar lactose as food.
Lactose  lactic acid
• This is called lactic acid fermentation
Souring of milk
• Bacteria feeds on
lactose producing pH
7
lactic acid.
• Milk becomes more 6
acid and its pH falls. 5
4
Days
1
2
3
4
5
6
Cheese and yoghurt production
• Lactic acid makes milk curdle
• Special strains of bacteria are used
in fermentation in curdling milk.
Flow diagram for the
manufacture of yoghurt
Bulk raw milk
Cool
Storage
4oC
pasteurisation
cooler
Packaging
Chiller 5oC
Incubation at
42oC for
6 – 8 hours
Cheese and yoghurt
• Cheese
– Bacteria added
• Yoghurt
– Milk curdles
– Bacteria
added to
– Rennin (enzyme) used to
pasteurised
separate milk into curds
milk
and whey
– Milk clots
– Whey run off
– Yoghurt
– Curds cut into blocks and
formed
mixed with salt to slow
– Put into tubs
bacterial growth
and stored in
fridge
– Packed into moulds